Floralturbation, the mixing of soil by the action of plants, is an important pedologic process in forested areas. The uprooting of trees, the most obvious form of floralturbation, is a natural process found in nearly all forested landscapes. The term uprooting is distinct from such terms as treethrow, treefall, and blowdown, which imply processes that may occur without soil disturbance, as in bole snap. Uprooting is exacerbated by shallow rooting, topographic exposure, weakened condition of the tree, certain cutting practices, and (or) low soil cohesion and shear strength. The root plate of an uprooted tree may deteriorate into a pit-mound pair, the size and shape of which depends on the characteristics of the root plate and the amount of backward displacement during uprooting. This paper (i) provides a synthesis of related terminology on the topics of treefall and uprooting, (ii) examines various lines of evidence for the widespread occurrence of uprooting, (iii) summarizes disturbance cycles for catastrophic uprooting events in different environments, (iv) discusses several examples of the economic import and scale of widespread uprooting events, and (v) reviews environmental factors and silvicultural practices that may lead to increased uprooting or can be used to minimize its likelihood.

This paper reviews the ecological effects of tree uprooting. In many forests, disturbance by uprooting is the primary means of maintaining species richness and diversity. Treefall may be due to exogenous factors or it may be endogenously created, although the former predominate. The canopy gap formed by downed trees is often vital to community vegetation dynamics and successional pathways, by providing high light niches (gaps) for pioneer species, by encouraging release of suppressed, shade-tolerant saplings, and through recruitment of new individuals. Nutrient cycling may be affected by uprooting as subsoil materials are brought to the surface, via additions of woody debris to the forest floor, through exposure of bare mineral soil, and by changes in throughfall chemistry. The influence of the resultant pit/mound microtopography on understorey herb distribution is largely due to microclimatic and microtopographic variation. Tree seedling distribution, however, is related to microtopography primarily through differences in soil morphology, nutrition, and moisture content of mound and pit sites.

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